MOTM 900

(text and images courtesy Synthesis Technology)

The MOTM-900 is a 3U wide, low-noise linear supply that accepts AC line inputs from 100 to 240VAC 50/60Hz (jumper selected) and outputs +-15VDC at 800ma. The easy-to-change fuseholder accepts standard 5mm x 20mm fuses. Instead of noisy 3-terminal regulators, the MOTM-900 uses a 723-based design, using a pre-assembled and tested Power-One supply. This makes assembly of the kit fast and almost fool-proof.

Each MOTM module uses a 4-pin connector called an MTA-156. These are "industry standard" connectors that have been in use for over 20 years. The MOTM-900 contains a special pc board that has 12 individual MTA male connectors. A 4-conductor, 18ga wire harness (part number PWR-20, included with each kit) connects the module to the MOTM-900. In this manner, a "star" power distribution scheme is used for lowest noise and avoiding ground loops. Since the average MOTM module draws 20ma from each supply, at 65% rated capacity (to keep the heat down) the MOTM-900 can power over 20 modules. An additional power distribution board can be purchased (see the catalog) to supply over 12 modules. In the past, "homebuilt" synthesizers with 3-terminal regulators have suffered from noise, hum, and crosstalk. The MOTM-900 design and power distribution system eliminates these problems, and will provide years of trouble-free service.

Specifications for the supply include:

LINE REGULATION: +-0.05% for a +-10% AC input change (very likely!) LOAD REGULATION: +-0.05% for a 50% load change (highly unlikely!) RIPPLE: 5mv pk-pk MAX. 1mv pk-pk typical